1. Field of the Invention
This invention lies in the field of the apparatus for ammonia synthesis.
More particularly, this invention concerns the design of the air injector head for the purpose of injection of air to mix with the process gas into a secondary reformer in the HABER process of ammonia synthesis.
2. Description of the Prior Art
In the prior art, the air injector head has been a refractory covered series of circumferentially spaced air tubes connected to a plenum at the bottom end of the air supply pipe. This is centered in the top opening of the reactor and the process gases are introduced at substantial velocity in the annular space around the air pipe. The downward flow impinges on the outwardly moving jets of air to turbulently mix and burn.
However, because of the limited number of outwardly flowing jets, there were not enough to fully intercept the process gas flowing down the annulus and, therefore, this gas would proceed at high velocity, which is unimpeded and unreacted, to impinge on the horizontal surface of the bed of catalyst, through which the hot gases, which are the products of combustion of the process gas with the air jets, to provide a uniform mixture of high temperature gas to flow downwardly through the bed of catalyst.
To the extent that part of the downflowing process gas in not intercepted by the air jets, that part impinges at high velocity onto the surface of the catalyst bed, causing turbulent movement of the catalyst, and forming many fines, which block the interstices in the catalyst bed and build up flow resistance.
This invention is directed to the improvement of the contacting between the air jets and the process gas in this portion of the processing in the synthesis of ammonia.